A method has been known in the past in which a surface of sealing resin chat seals a semiconductor chip is covered with a conductive layer in order to give a shielding function to a semiconductor package of the semiconductor chip mounted on an interposer. Meanwhile, a technique for implementing an internal antenna module has been proposed in which an aperture extending to a conductive portion of an interposer from a principal surface portion of a conductive layer for shielding (a surface facing a component mounting surface of the interposer) via a side surface portion thereof (a surface facing a side surface of the interposer) is provided to cause this aperture to function as a slot antenna.
However, according to the conventional technique, approximately a half of the slot antenna is constituted by the aperture provided at the conductive portion of the interposer and thus, the interposer has a large antenna-occupied area by the aperture portion. As a result, an area of an antenna section where a wiring pattern for a signal line cannot be provided increases at the conductive portion of the interposer, thereby having caused a problem in which reduction in size of the interposer is difficult to achieve.